The present invention relates to particulate material handling systems, and more particularly to such a fluid pumping system for pumping particulate material at an optimized capacity.
Particulate material handling and processing systems, such as powder material handling systems, are well known, and typically include the unloading, conveyance and feeding, for example, of powder material from a supply source to an output location. In the case of powder material, such unloading, conveyance and feeding usually include use of a pneumatic pump as disclosed for example in U.S. Pat. No. 5,518,344. A typical powder material conveyance or conveying system also includes a hollow line or conduit having intake and discharge ports across which there is often a need to regulate not only the rate of powder material flow, but also the state or condition of the powder material where powder material can undesirably pack.
Conventionally, purging fluid or air stays on continuously so as to dilute the particulate material being pumped. Although useful in fluidizing the particulate material to be pumped out, such purging fluid or air has been found to reduce the rate, and hence the amount, of particulate material being loaded to be pumped. This of course results in an undesirable loss of system throughput capacity.
For example, it has been found that when using a pneumatic diaphragm type pumping system, the system suffers significant disadvantages if it is necessary for some reason to substantially cut down on or reduce the level of the motive air. According to these disadvantages, the conveying capacity of the system usually is slowed down. If there is not sufficient purging fluid or air present, it undesirably causes particulate material to pack not only in the conveying conduits, but also in the diaphragm pump housing itself, thereby undesirably causing the pump to become significantly inefficient even to the point it stops.
There is therefore a need for a fluid pumping system for pumping particulate material at an optimized capacity, and without the disadvantages of conventional systems.
In accordance with one aspect of the present invention, there is provided a fluid pumping assembly for pumping particulate material includes a pump housing defining a pump cavity including a pumping chamber for handling particulate material, a motive fluid chamber, and a moveable diaphragm The fluid pumping assembly also includes devices for loading particulate material into the pumping chamber, and for injecting a high pressure, high volume purging fluid into the pumping chamber. Further, the fluid pumping assembly includes a control system having a control valve for shutting off flow of high pressure, high volume purging fluid into the pumping chamber when particulate material is being loaded into the pumping chamber, thus enabling dense phase loading of particulate material, and thereby optimizing a particulate material pumping capacity of the fluid pumping assembly.